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Subject: [Bug target/100799] Stackoverflow in optimized code on PPC
Date: Wed, 20 Jul 2022 17:59:08 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D100799

--- Comment #13 from Segher Boessenkool <segher at gcc dot gnu.org> ---
(In reply to Alexander Grund from comment #11)
> Some more experiments with GCC 10.3, OpenBLAS 0.3.15 and FlexiBLAS 3.0.4:
>=20
> Baseline: Broken at -O1, working at -Og
>=20
> I got it to break with "-Og -fmove-loop-invariants".
> Then it worked again by adding "-fstack-protector-all".

Both are great info!

> But that is
> seemingly not advisable:
> https://developers.redhat.com/blog/2020/05/22/stack-clash-mitigation-in-g=
cc-
> part-3

-fstack-protector-strong is cheap enough that you can (and perhaps should)
enable it almost always.  Some distributions do this even?

-fstack-check=3D is an Ada thing.  -fstack-clash-protection is a different =
thing
as well (that's what that article is about).

Enabling ssp is not a great workaround of course, it is much to roundabout;
and I suspect the only reason it works is because it changes the stack layo=
ut.
Still, useful info, thanks :-)=